F04B43/00—Machines, pumps, or pumping installations having flexible working members

F04B43/12—Machines, pumps, or pumping installations having flexible working members having peristaltic action

F04B43/1253—Machines, pumps, or pumping installations having flexible working members having peristaltic action by using two or more rollers as squeezing elements, the rollers moving on an arc of a circle during squeezing

F04B43/1276—Means for pushing the rollers against the tubular flexible member

Abstract

The invention concerns a miniature peristaltic pump comprising a rotor (109) provided with three turning rollers (110), a support piece with a rounded portion arranged substantially concentric to said rotor and against which, when operating said rollers are brought to compress a flexible pipe connected to a reservoir of solution to push it outwards and means for automatically compensating positional deviations between the rollers and said support piece. Each roller (110) comprises a substantially cylindrical body (127) and a spindle (126) on which said body is rotatably mounted. The ends of the roller spindles are located in oblong apertures (128) radially recessed in the rotor. The compensating means comprise two springs (129) arranged at the respective ends of said spindles and comprising a central part (130) concentric to the rotor and three curved spring arms (132), one for each roller, with one end connected to said central part and the other end bearing on the corresponding end of a roller spindle to push it outwards and thus enable it to exert a substantially constant force of pressure. The invention is useful for the subcutaneous or intravenous injection of medicinal solutions.

Description

MINIATURE PUMP PERISTALTIC

The present invention relates to peristaltic pumps It relates more particularly to a miniature peristaltic pump for injecting drug solutions

The miniature pumps or micropumps for medical use have been known for several years. Light and of small dimensions, they are carried by the discretely and without discomfort the patient and allow to administer, subcutaneously or intravenously, continuously or according to a predetermined program controlled amounts of drug solutions, without that it is provided in bed and connected to a cumbersome, expensive and noisy apparatus

Such pumps are most often rotary peristaltic type whose principle is to have a deformable plastic tube connected to a reservoir containing the solution and crush locally against a support part rounded to means of pressing rollers mounted on a rotor driven by a motor acting through a gear train. Liquid is thus drawn from the tank and pumped to the outlet to be injected into the patient

When designing such pumps, it is particularly important to ensure the optimization of the coupling between the rollers and the pipe they come in turn to crash against the bearing piece

Measurements have shown that the minimum pressure of a roller of 5 mm diameter necessary for flowing a liquid in a plastics pipe having an internal diameter of 1 47 mm and an outer diameter of 1 96 mm is 95 gr. The corresponding pulling force exerted by the roller is 15 g Pressure on the roller can be up to 150 grams without proportionally increasing the passing traction while only 15 to 20 gr But beyond this limit the tensile force increases very rapidly it happens, in fact, 50 gr to a pressure of 200 g, after which the measurements become impossible such findings are easily explained by the fact that once the hose compressed up 'to its complete closure, any increase in pressure causes deformation of the plastic material and the corresponding tensile force then increases in relation to its modulus of elasticity

Thus, any position vaπation of the roller relative to the pipe beyond that which performs its sealing strongly biases the roller-carrying rotor and its drive motor, which quickly causes a blockage and thus the stopping of the pump. The effect is even more marked in the miniature pumps that are equipped with engines obviously less powerful than non-portable pumps.

Conversely, any roller position vaπation below that which performs its shutter does not allow a sufficient flow of liquid

So it is very important for a safe operation pump, that the distance between the roller of the bearing part is fully defined and consistently to avoid outright blockage or irregular and insufficient flow.

So if the support piece and the roller are fixed, extremely strict manufacturing tolerances required and thus increase significantly the cost of the pump.

It is therefore preferable to accept lighter tolerances and to provide means to automatically compensate for any positional deviation between the supporting part and the roller.

EP 388 787 shows a bearing piece having the form of a hook pivoted at one of its ends by a pin and is pressed against the hose by means of a compressed spring by a screw This part of support being substantially always biased by two rollers, it can not ensure the compensation of positional deviations for each roller separately. EP 447 909 shows that the rollers are mounted on their shaft with a slight clearance allows them a certain radial clearance, and that individual leaf springs acting directly on their central portion, bias the outwardly Such an arrangement has the dual disadvantage of complicating the assembly of the rotor and cause it to slide over the pipe rather than turning II is also indicated in this document, the springs can be replaced by a single elastic piece, which is however no descπption provided and they can be downright omitted because the rollers are moved radially by the inherent elasticity of the pipe itself This shows that the importance of the problem has not been fully understood

Said cassette pumps are the most common for medical applications has two components, on the one hand, the pump itself, with the motor, the control electronics, battery and the pump head formed by the rotor and pressure rollers and, secondly, the cassette which clips on the pump and comprises the pipe and the supporting part the reservoir is either integrated in the cassette when it is of small dimensions, is freely disposed in the extéπeur when large

Pumps of patents EP 447 909, EP 521 184 and WO 94/06491 are of this type

In all three cases, the cassette includes, assembled permanently, the pipe, the support piece and the tank pumps the two EP patents can only be used once because, once mated, the two modules can be uncoupled. At the end of treatment or when the cassette is empty, it is thrown everything, including therefore the engine, the pump head, the bearing part, the gear train and the circuit which nevertheless are capable of operating at as for the new pump of the WO, the cassette is oneway along his tank Thus, in these three pumps, thrown components that could still be used as such since they are not worn and were never in contact with the medication injected into the patient

Documents US 4,817,057 and EP 120 284 disclose, in addition, peristaltic pumps of large size cassette, i.e. non-portable Although the tube can be easily inserted into - or removed from - the tape, it is provided with a connection piece to the nozzle from the reservoir and its portion subjected to the peristaltic action is specially designed to withstand prolonged exposure to the compression effect of the rollers such a construction presents disadvantages because not only it does not prohibit the reuse of the tube to administer different drug solutions to different patients, but, interconnection operations of the two tubes increase the risk of contamination of the circuit by bactéπes.

Another important problem in the design of such pumps is that of purging pipes, ie the evacuation of the air they contain even before the introduction of the needle in patient the rotational speed of the rotor is very low, generally less than 1 turn / minute, this operation should not take too long, be performed by rapidly rotating the rotor by external means in EP 388 787 there is provided a wheel that is integral with the rotor and comprises a series of holes into which may be inserted the point of a pen, for example, to rotate the wheel quickly the solution is certainly interesting but no provision n is provided to prevent this operation from damaging the gear train

The present invention aims to provide an improved miniature peristaltic pump that is free of the disadvantages of the prior art pumps

Pénstaltique miniature pump according to the invention comprises - a rotor equipped with at least two rotating rollers,

- means for driving said rotor,

- control means of said driving means,

- a support piece provided with a rounded portion arranged substantially concentnque to said rotor and against which, in use, lesdit roller compresses flexible tubing connected to a solution tank to push it outwards and

- means for automatic compensation of positional deviations between the rollers and said support part

This pump is primarily characterized in that each roller comprises a substantially cylindrical body and a shaft on which said body is rotatably mounted, in that the rollers of the axes of the ends are placed in oblong openings formed radially in the rotor and in that said compensating means comprise two springs arranged at the respective ends of said axes and comprising a concentric central portion to the rotor and two curved spring arms, one for each roller, one end of which is connected to said central portion and whose other end is bearing on the corresponding end of a roller shaft to push it outwards and thus enable it to exerœr on the pipe a substantially constant compressive force.

Other features of the invention emerge from the description which follows, with reference to the accompanying drawings and giving, as explanatory but not limiting, a preferred embodiment of this pump. In these drawings:

As shown in Figures 1 to 5, the miniature pump according to the invention consists of three modules, a pump module 100, a reservoir unit 200 and cartridge unit 300 which will be also called respectively pump, reservoir and cassette. The reservoir 200 is plaœ detachably into the cassette 300 which, in turn, is coupled releasably to the pump 100.

To fix ideas and purely by way of example, the pump assembly has a length of 110 mm, a width of 55 mm and a thickness of 13 mm for a 10 ml reservoir capacity. The pump module 100, shown in Figure 1, comprises a rigid plastic housing 101 whose bottom is extended on one side to form the basis of two parallel sliders 102 for the implementation of the module tape 300 in the manner a drawer As shown better in Figure 5, each slide 102 is an aperture 103 in which is provided a flexible tongue 104 forming a push-button intended to release the cassette when it is to be uncoupled from the pump

Supéπeure on its face, the housing 101 includes a button "START / STOP" key 105 for controlling the starting and stopping of the pump, a button "BOLUS" 106 for initiating the administration of additional doses of solution, an alarm sound 107 and an LCD display 108

The housing 101 reveals, between the two sliders 102, a rotor 109 having three rollers 110 and forming the head of the pump A detailed description will be given later together with that of its drive means

The reservoir module 200, shown in Figure 2, is formed of a plastic bag 201 having, in the embodiment shown, a volume of 10 ml and a flexible plastic tube 202 having one end connected to the pocket and the other intended to be connected to an injection needle subcutaneously or intravenously, is closed by a stopper 203 the pipe further comprises, in thickness, two rigid molded fittings shaped elbow 204 and 205 for its snap-in cassette 300, as will become better later

The tape module 300, shown from below in Figure 3, is rigid plastics sends and includes a housing 301 for receiving the plastic pack 201 has substantially the same thickness and the same width as the housing 101 and has bottom side , 302 mounted on a two hinges 303 and cover provided at the other end, tabs 304 assure its closure by clipping the housing 301 is extended by a plate 305 shaped and sized to take place, such as a drawer, between the sliders 102 Two tongues of the housing 306, arranged on their sides, permit its clipping by the securing of their ends into openings 103, as also shown in Figure 5 the plate 305 is drilled, the bottom side by a housing 307, in the form general U dimensioned to receive the rotor 109 of the pump module II comprises, for this purpose, a rounded central portion 308 approximately 120 degrees and the radius is slight ment greater than that of the circle traveled by the outer surface of the rollers 1 0. It is on this rounded portion 308, in operation, the three rollers come in turn to crush the flexible tube 202. A rounded additional clearance 309 is provided around of the portion 308 to receive the lower portion of the rotor 109, of larger diameter than the circle covered by the rollers, as will be further

The bottom of the housing 307, which forms the upper wall of the module, is drilled in the center of the rounded portion 308, a circular orifice 310 with respect to where takes place the axis of the rotor 109 to allow the purge the pump before use, as will be described below This hole is closed by a cover 311 sliding in a recess 312 of the upper wall of the module

Plate 305 also comprises two channels 313 and 314 each formed in the bottom of one side parallel thereto. The channel 313 connects the housing 301 to the front of the housing 307. Prior to uncapping therein, it has a bent portion 315 of larger diameter formed and dimensioned to receive and hold by clipping the rigid connector 204 of the hose 202. the channel 314 from the front of the housing 307 opposite happens where the other channel 313 and opens to the outside after a bent portion 316 of larger diameter, and formed sized to receive and hold by clipping the rigid tube 205 of tube 202.

Referring now more particularly to Figures 4, 5 and 6 demonstrate how the three modules described above mate to form the miniature pump according to the invention

The reservoir unit 200 is, first, placed in the cassette unit 300 The plastic pack 201 is inserted into the slot 301 and the hose 202 positioned in the channels 313 and 314, ensuring that its two rigid connections 204 and 205 take place and can snap into place respectively in the bent portions 315 and 316 of the tray 305 After closing the lid 302, it then remains to insert the cassette into the sliders 102 of the pump unit 100 until that the tongues 306 are hooked into the openings 103 (Figure 5) the end of the lower part of roter 109 occupies the clearance 309 of the plate 305, while the central portion of the flexible tube 202 is automatically trapped between the rotor 109 and the support member 308 When the rotor is rotated in the direction of arrow F (counterclockwise of a watch), the rollers January 10 will alternately compπmer tubing 102 to push outwardly the solution contains

The pump being charged, the plug 203 of the tube is removed and replaced, as shown in Figure 6, by a pipe 601 terminating in a needle 602 Before introducing it into the patient, it is imperative to evacuate the air in the circuit and have it reach the injection solution the normal speed of rotation of the rotor 109 is very low (0625 rev / minute), as will be described later, the purge operation must not to take too much time, be done by rapidly rotating the rotor by external means supéπeure the end of the shaft of the latter has, for this purpose, a shaped opening 134 appearing in the opening 310 of the cassette and which, with the aid of a suitable tool, the rapid rotation of the rotor until the drops of the solution to be injected out of the needle 602 the latter may then be introduced into the patient, after whereby the pump is switched on by pressing button 105 which controls the rotation of the rotor 109 by means which will be described in detail below

At the end of treatment, the uncoupling of the pump 100 and cassette 300 modules is achieved by pressing the two buttons 104 so as to disengage the tabs 306 of the openings 103 The cassette can then be removed by sliding it outwards before remove the reservoir 200 which can be replaced by another, the cassette and the pump can be reused for further processing

The module pump 100 will now be déent with reference to Figures 7 to 1 1, which show the rotor 109, a stepping motor 1 1 1, a gear set January 12 coupling the motor rotor, an electronic control module 1 13 and a rod cell 1 14

The rotor 109, shown in detail in Figures 8 and 9, comprises a circular base 1 15 provided with a toothing Device 1 16 and mounted for free rotation on a pivot 117 belonging to the bottom of the housing 101 A ring 1 18 of slightly smaller outside diameter than thy base 1 15 is mounted on the latter and fixed to it by tenons January 19 this ring has inwardly, three flexible arms 120 molded within its mass at 120 ° one from each other and forming pawls whose end cooperates with the péπphéπe sawtooth 121 of a wheel 122 this is the basis for a roller carrier cylindπque plate 123 mounted on the axis of the base 115 around which it can rotate freely

Péπphéπque the wall of the tray 123 has a curved profile to the intéπeur 124 so as to form a channel for the passage of the hose 202 The same wall is also pierced by three housing 125 U-shaped arranged at 120 ° one from the other for receiving the three rollers 1 10 of compression of the pipe

1 each roller 10 is formed of a shaft 126 and a cylindπque body 127 mounted on the axis about which it can rotate freely Both ends of this axis take place in oblong openings 128 radially in the portions of the tray 123 forming the plane walls and supéπeure lower housing 125. the rollers are kept upright, i.e. with their axis parallel to the rotor axis, and subjected to a radial force directed towards the exténeur through two springs 129 disposed on either side of the tray 123 Each spring includes a rigid central portion 130, of substantially tπangulaire fixed to the plate concentπquement to it by rivets 131 and three flexible curved spring arms 132 whose free ends are supported on the respective ends of the axes 126 and push them towards the exténeur so that the rollers January 10 exert on the pipe 202 a substantially constant force, fix ed to 120 grams in the example described The positioning errors on the rollers and the hose, due to unavoidable manufacturing defects, are automatically compensated, thus avoiding excessive or insufficient compression of the tube 202

The plate 123 extends axially toward the top by a protrusion 133 extending through the central portion 130 of spring 129 supéπeur This protuberance is drilled with the shaped aperture 134 already cited in which can be introduced, through the circular opening 310 of the cassette, the profile tip correspondingly of a tool (not shown) for the rapid rotation of the plate to effect purging of the pump the rotation of the rotor 109 is provided by the stepper motor 111 which is the kind phase conventional bipolar and rotates at 16 revolutions / second with two steps per revolution. The core-coil and stator, respectively designated by references 135 and 136 are fixed on legs formed in the bottom of the housing 101 by two screws 137 its rotor 138 pivots between the housing base and a bridge 139 secured by screws 140 of feet integral with the bottom of the housing.

The rotor 138 carries a pinion 141 meshing with a wheel 142 forming the first movable gear train 112. The gear 143 of the wheel itself meshes with a wheel 144, the pinion 145 finally engages with the peripheral teeth 116 of the base 115 of the rotor 109 to rotate at a speed of 0625 rpm. The wheels 142 and 144 rotate as the rotor 138, between the housing base and the bridge 139. The latter ends, after a bend, by two arms 146, not shown in Figure 9, which comprises a common end circular opening in which is held and rotates the projection 133 of the rotor 109.

In operation, when the base 115 of the rotor is driven in the direction of arrow F by the motor 111 through the gear 112, it rotates with it the ring 118 which is secured to the three pawls

120 of this latter then interact with the periphery sawtooth 121 of the wheel 122 to rotate and with it the roller carrier plate 123 which forms the basis rollers January 10 are thus alternately compressing the pipe 102 to push the liquid contained therein in the direction of the injection needle 602

When to realize the purge manifolds, rotating the carrier rollers tray 123 with the aid of an appropriately shaped tool inserted into the opening 134, the base 1 15 and the ring 1 18 become fixed, because braked by the torque retention of the motor 1 1 1 and its gear train 1 12 A clutch is automatically carried out between the ring 1 18 and the wheel 122 of the fact that the rotation thereof causes the expulsion of the three pawls 120 sawtooth

121 The roller carrier plate 123 can be quickly turned no effect on the gear and motor tram

The electronic control module 113, shown in Figure 10, is based on a circuit board 147 fixed under the upper face of the case and having buttons 105 and 106, the buzzer 107 and the LCD 108. The board also has a microprocessor system 148 integrating the following main functions: voltage doubler, quartz time base, memory, LCD driver and sound generator. This microprocessor being of a known type, such as EPSON 62L35, it will not be described in detail. All these components and the battery 114 and the motor winding 111 are interconnected in the simplified diagram of Figure 11.

The microprocessor 148 is programmed according to well known methods to the skilled man, that the assembly operates as follows.

When the switch 105 is actuated for the first time, it triggers the operation of the microprocessor 148 which, under the command of a registered administration program in the memory, applied to the terminals of the stepper motor 111 of the drive pulses to the frequency of 32 Hz causing it to rotate at the speed of 16 revolutions / sec. The rotor roller holder 109 is then driven at the speed of 0625 rev / min. The pump operation is interrupted when the switch 105 is activated a second time

To fix ideas, with a radius of rotation of the roller-carrying plate of 10.44 mm and a speed of 0625 rev / min, the solution flows through the tubing at a rate of 41 mm / min. By choosing a pipe having an inner diameter of 1.47 mm, the instantaneous flow rate of the pump is thus 69.54 mm 3 / mιn, 100 cm3 / day.

The microprocessor 148 also enables, in response to actuation of the button 106, to escape the administration program stored in memory for controlling the injection of an additional amount determined solution (bolus). This procedure is particularly intended treatment painkiller.

The pump is also provided with means for actuating the buzzer 107 and / or the LCD 108 in case of malfunction Failure of the program, stop, obstruction of the needle end of battery life .. . These means are not subject of this patent, they will not be described. We finally refer to Figure 12, which shows a variant of the cassette unit 300 for treatments requiring large amounts of injection solution. The cassette can certainly be extended to accommodate a larger tank, but if the volume is exceeding 20 ml, the size of the pump may make it impractical For this reason, the cassette unit of Figure 12 includes only the plate 305 described in FIG 3, the same references being used to designate the same elements. The reservoir module then includes a pocket 206 of large volume, which is not inserted in the cassette but only connected thereto by a flexible tube 202 longer identical to that described in Figure 2.

Claims

1 miniature peristaltic pump comprising

- a rotor (109) equipped with at least two rotating rollers (110), - driving means (111 112) of said rotor,

- control means (113) of said drive means,

- a support piece provided with a rounded portion (308) substantially concentrically arranged with said rotor and against which, in operation, said rollers come compressing a hose (202) connected to a solution tank (201) for pushing thereof to the exténeur and

- means for automatic compensation of positional deviations between the rollers and said workpiece support, said pump being characterized in that each roller (110) comprises a body (127) substantially cylindπque and an axis (126) on which said body is rotatably mounted, in that the ends of the axes of the rollers taking place in oblong openings (128) radially formed in the rotor and in that said compensation means comprise two springs (129) disposed at respective ends of said axes and comprising a central portion (130) concentric with the rotor and two spring arms (132) recurved, one for each roller, one end of which is connected to said central portion and whose other end bears on the corresponding end of a pin follower to push it towards the exténeur and thus enable it to exert on the tube a substantially constant compressive force

2 Miniature peristaltic pump according to claim 1, characterized in that

- the rotor and its rollers, said drive means and said control means form a first module (100), said pump module,

- the supporting part is part of a second module (300), said cartridge unit,

- said modules are each provided with means allowing their coupling and

- the cassette module has means for receiving interchangeably the pipe (202) which is integral part of the reservoir (201) and automatically positioning said pipe so that when the coupling of the two modules it applies against said rounded portion (308) to be compressed by lesdit rollers, the hose and the reservoir thus forming a third module (200), said reservoir module, which can be easily exchanged with another after use 3 miniature peristaltic pump according to claim 2, characterized in that the cassette module (300) comprises a tray (305) engages, like a drawer, in the pump module and pierced with a housing (307), generally U-shaped and sized to surround the rotor and whose rounded bottom (308) constitutes the supporting part of the pipe and in that the means for receiving and positioning said tubing comprise a first (313) and a second channel (314) formed along respective sides of said plate, said channels having an open end on the outside of the plate and their other ends opening away from each other in the inlet of said housing

4 Miniature peristaltic pump according to claim 3, caractéπsée in that said channels comprise means for retaining said pipe by encfipsage

5 Miniature peristaltic pump according to claim 4 characterized in that said means for retaining the tubing consist of elbowed portions (315, 316) of said channels, shaped and dimensioned so that portions (204, 205) of corresponding shape of said tube are take place and there are retained by clipping

6 Miniature peristaltic pump according to one of claims 2 to 5, characterized in that the cassette module is fixed in the pump unit by clipping of its plate in slides (102) of said pump unit

7 Miniature peristaltic pump according to one of claims 2 to 6 characterized in that the cartridge unit further comprises, a housing (301) for receiving the solution tank

8 Miniature peristaltic pump according to one of the preceding claims, characterized in that it further comprises, means for rotating said rotor by external action in order to achieve the purge pipe

9 Miniature peristaltic pump according to claim 8, characterized in that the rotor is made in two superposed concentric parts the first of which is coupled to said drive means and the second carries the roller and in that it further comprises, means for clutch-disengaging whereby

\ 4 - in normal operation, its two parts cooperate to achieve its rotation by its driving means,

-when is rotated by external action, said parts are automatically uncoupled

10 Miniature peristaltic pump according to claim 9, caractéπsée in that the first part of the rotor comprises a toothed wheel (115) cooperating with said driving means, in that its second part also comprises a toothed wheel (122) forming the base tea nosepiece (123) and in that said clutching-declutching means comprise a crown (118) fixed to the toothed wheel (115) of the first part concentπquement to it, surrounding the gear wheel (122) of the second part and having, towards the intéπeur, at least one flexible arm (120) forming a pawl and whose end cooperates with the toothed wheel of the second part

11 Miniature peristaltic pump according to one of claims 8 to 10, characterized in that the means for rotating the rotor by external action include a protuberance (133) extending the axis of the rotor and pierced with a shaped opening ( 134) for receiving the end of a correspondingly shaped tool